MIWA U9.LDSP is malfunctioning and has a key Unlocking the entrance door

"The entrance cylinder does not turn due to long absence"

Apparently he had been away for nearly two months, but when he returned home, he couldn't turn the key when he put it in. When I checked it, it was indeed hard and wouldn't turn.

In such a case, first proceed by cleaning the cylinder. Then it started spinning right away. I unlocked it and checked the thumbturn side, but it had a cover on it. The customer didn't know about it (didn't care about it), so it must have been installed by the previous resident. It was the same cover as the other day. I hate.